我试图了解 MySQL。我从在线信息中学到了很多东西，但是，我有点坚持理解 JOINS 的工作原理以及如何融入 DataTables 代码。
我有这个表结构：
而这个 MySql 语句：
SELECT leads.lead_id, leads.date_time, clients.username, courses.course_type, courses.location_name, CONCAT(first_name,' ',surname)
FROM courses
LEFT JOIN leads ON leads.lead_get_course_id = courses.course_id
LEFT JOIN clients ON clients.client_id = courses.course_get_client_id
WHERE leads.checked_by_admin = 'No'
当我在dreamweaver中测试它时一切正常，但是当我尝试将它应用于DataTables代码时，我在'字段列表'中得到未知列'leads.lead_id'
这是我的数据表代码：
<?php
/*
* Script: DataTables server-side script for PHP and MySQL
* Copyright: 2010 - Allan Jardine
* License: GPL v2 or BSD (3-point)
*/
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Easy set variables
*/
/* Array of database columns which should be read and sent back to DataTables. Use a space where
* you want to insert a non-database field (for example a counter or static image)
*/
$aColumns = array(
"leads.lead_id",
"leads.date_time",
"clients.username",
"courses.course_type",
"courses.location_name",
"CONCAT(first_name,' ',surname)"
);
/* Indexed column (used for fast and accurate table cardinality) */
$sIndexColumn = "leads.lead_id";
/* DB table to use */
$sTable = "courses";
$sJoin = 'LEFT JOIN leads ON leads.lead_get_course_id = courses.course_id';
$sJoin = 'LEFT JOIN clients ON clients.client_id = courses.course_get_client_id';
/* Database connection information */
$gaSql['user'] = "root";
$gaSql['password'] = "tommy";
$gaSql['db'] = "testingsiasite";
$gaSql['server'] = "localhost";
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* If you just want to use the basic configuration for DataTables with PHP server-side, there is
* no need to edit below this line
*/
/*
* MySQL connection
*/
$gaSql['link'] = mysql_pconnect( $gaSql['server'], $gaSql['user'], $gaSql['password'] ) or
die( 'Could not open connection to server' );
mysql_select_db( $gaSql['db'], $gaSql['link'] ) or
die( 'Could not select database '. $gaSql['db'] );
/*
* Paging
*/
$sLimit = "";
if ( isset( $_GET['iDisplayStart'] ) && $_GET['iDisplayLength'] != '-1' )
{
$sLimit = "LIMIT ".mysql_real_escape_string( $_GET['iDisplayStart'] ).", ".
mysql_real_escape_string( $_GET['iDisplayLength'] );
}
/*
* Ordering
*/
if ( isset( $_GET['iSortCol_0'] ) )
{
$sOrder = "ORDER BY ";
for ( $i=0 ; $i<intval( $_GET['iSortingCols'] ) ; $i++ )
{
if ( $_GET[ 'bSortable_'.intval($_GET['iSortCol_'.$i]) ] == "true" )
{
$sOrder .= $aColumns[ intval( $_GET['iSortCol_'.$i] ) ]."
".mysql_real_escape_string( $_GET['sSortDir_'.$i] ) .", ";
}
}
$sOrder = substr_replace( $sOrder, "", -2 );
if ( $sOrder == "ORDER BY" )
{
$sOrder = "";
}
}
/*
* Filtering
* NOTE this does not match the built-in DataTables filtering which does it
* word by word on any field. It's possible to do here, but concerned about efficiency
* on very large tables, and MySQL's regex functionality is very limited
*/
/* */
/* */
$sWhere = "";
if ( isset($_GET['sSearch']) && $_GET['sSearch'] != "" )
{
$sWhere = "WHERE (";
for ( $i=0 ; $i<count($aColumns) ; $i++ )
{
$sWhere .= $aColumns[$i]." LIKE '%".mysql_real_escape_string( $_GET['sSearch'] )."%' OR ";
}
$sWhere = substr_replace( $sWhere, "", -3 );
$sWhere .= " AND checked_by_admin='No'";
$sWhere .= ')';
}else{
$sWhere = "WHERE checked_by_admin='No'";
}
/* Individual column filtering */
for ( $i=0 ; $i<count($aColumns) ; $i++ )
{
if ( $_GET['bSearchable_'.$i] == "true" && $_GET['sSearch_'.$i] != '' )
{
if ( $sWhere == "" )
{
$sWhere = "WHERE ";
}
else
{
$sWhere .= " AND ";
}
$sWhere .= $aColumns[$i]." LIKE '%".mysql_real_escape_string($_GET['sSearch_'.$i])."%' ";
}
}
/*
* SQL queries
* Get data to display
*/
if($sWhere != ""):
$sWhere .= " AND checked_by_admin='No'";
endif;
$sQuery = "
SELECT SQL_CALC_FOUND_ROWS ".str_replace(" , ", " ", implode(", ", $aColumns))."
FROM $sTable
$sJoin
$sWhere
$sOrder
$sLimit
";
$rResult = mysql_query( $sQuery, $gaSql['link'] ) or die(mysql_error());
/* Data set length after filtering */
$sQuery = "
SELECT FOUND_ROWS()
";
$rResultFilterTotal = mysql_query( $sQuery, $gaSql['link'] ) or die(mysql_error());
$aResultFilterTotal = mysql_fetch_array($rResultFilterTotal);
$iFilteredTotal = $aResultFilterTotal[0];
/* Total data set length */
$sQuery = "
SELECT COUNT(".$sIndexColumn.")
FROM $sTable
";
$rResultTotal = mysql_query( $sQuery, $gaSql['link'] ) or die(mysql_error());
$aResultTotal = mysql_fetch_array($rResultTotal);
$iTotal = $aResultTotal[0];
/*
* Output
*/
$output = array(
"sEcho" => intval($_GET['sEcho']),
"iTotalRecords" => $iFilteredTotal, // HERE FOR MASK TOTAL ENTRY not necerrary for others customers
"iTotalDisplayRecords" => $iFilteredTotal,
"aaData" => array()
);
while ( $aRow = mysql_fetch_array( $rResult ) )
{
$row = array();
for ( $i=0 ; $i<count($aColumns) ; $i++ )
{
if ( $aColumns[$i] == "version" )
{
/* Special output formatting for 'version' column */
$row[] = ($aRow[ $aColumns[$i] ]=="0") ? '-' : $aRow[ $aColumns[$i] ];
}
else if ( $aColumns[$i] != ' ' )
{
/* General output */
$row[] = $aRow[ $aColumns[$i] ];
}
}
$row[] = "<span style='cursor:pointer'><img src='../images/more-info.png' alt='more info' onClick='javascript:my_onclick({$row[0]});'/></span>";
$row[] = "<a href='../leads/actions/approve-lead.php?lead_id={$row[0]}'><img src='../images/approve.png' alt='' /></a>";
$row[] = "<a href='../leads/actions/delete-lead.php?lead_id={$row[0]}' class='delete_link'><img src='../images/delete.png' alt='' /></a>";
$output['aaData'][] = $row;
}
echo json_encode( $output );
?>
任何关于我为什么会收到此错误的信息都会很棒！